This invention relates to a door and method of manufacturing same, and more particularly to an exterior steel door that is inherently stronger and improved in that it is less susceptible to water absorption and deformation due to its specific construction and manufacturing process.
Steel doors are generally constructed with steel sheeting covering each side of a frame made of wood or metal. The four surrounding frame members (stiles and rails) are normally made of wood, but sometimes steel. The wood stiles and rails are exposed on perimeter sides allowing environmental elements such as rain, snow, etc. to deteriorate the door and the door finish. Other problems of manufacture and cost arise when trying to position two perimeter stiles and two perimeter rails that have to be dimensionally accurate in length, width, and diagonal while attaching the embossed steel skin on a frame assembly.
There are several U.S. patents which disclose prior art steel doors, with the following U.S. patents being exemplary of such doors: U.S. Pat. No. 4,148,157 to Franc; U.S. Pat. No. 4,152,876 to Seely; and U.S. Pat. No. 4,550,540 to Thorn. The patent to Franc (U.S. Pat. No. 4,148,157) discloses a metal clad door including an internal metal frame, two external panels of metal on each side of the frame, a sheet of insulating material such as foam filling a space defined by the frame and the two external panels, and a wooden edging surrounding the external panels to provide easy fitting and adjustment by the planing of the wooden edges. The patent to Seely (U.S. Pat. No. 4,152,876) discloses a metal faced door including a wooden frame, a cavity defined by the wooden frame, a foam core within the cavity, and a pair of metal panels adhered to the foam core and wooden frame, with the wooden frame being adaptable for trimming for fitting purposes. The patent to Thorn (U.S. Pat. No. 4,550,540) discloses a compression molded door comprising a rectangular perimeter frame made of wood, a foam core positioned within the rectangular perimeter frame, and a pair of skins or panels adhered to the sides of the foam core with the wood perimeter frame being adapted for trimming for fitting purposes.
The prior art also consists of U.S. Pat. No. 5,853,512 to McKinney and which is assigned to the Assignee of the instant invention. The McKinney patent discloses a method of fabricating unitary framed foam panels wherein frame members are fabricated by forming metal stock into a cross-sectional channel configuration, cutting and swaging the channels into predetermined lengths to provide frictional interconnection at the corners thereof upon assembly of the frame members into a rectangular frame configuration, and molding a foam panel within the rectangular frame. The framed foam panel disclosed by McKinney has some characteristics similar to the characteristics of the framed foam panel incorporated in the present invention.
The present invention relates to a rectangular door and method of manufacturing same. The door is generally comprised of a steel-framed foam core assembly and a pair of skins or coverings. The steel-framed foam core assembly generally comprises a pair of vertical stiles and a pair of horizontal rails or headers. Each stile and each rail has a swaged end and an unswaged end with the swaged end of each stile being joined to the unswaged end of an adjacent rail and the swaged end of each rail being joined to the unswaged end of an adjacent stile to provide a generally rectangular frame for supporting a foam core. The foam core includes one or more inserts for providing reinforcement to the door where hardware, such as knobs, locks and hinges, might be mounted to the finished door. The skins or coverings are preferably made of metal or a rigid plastic which are secured to the outer faces of the steel-framed foam core assembly to expose approximately one-eighth inch (xe2x85x9xe2x80x3) of the two stiles and two rails to provide a border around the periphery of the steel-framed foam core assembly. The steel frame, foam core, and the skins combine to provide a unitary door of exceptional rigidity and strength and are designed for rapid and economical assembly when employing the unique method of manufacturing the steel door of the present invention.
Accordingly, it is an object of the present invention to provide an improved door which can be assembled rapidly and economically from readily available components.
It is a further object of the present invention to provide an improved door including stiles and headers pre-cut to predetermined sizes, each having swaged and unswaged ends, joined together to form a frame core assembly to be filled with molded foam and having skins applied to the outer faces of the steel frame core assembly.
It is still a further object of the present invention to provide an exceptionally rigid and sturdy door designed for rapid and economical assembly.
These and other objects and advantages of the present invention will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings, specification, and claims.